Facile thermal activation of non-reactive cryptocrystalline magnesite and its application on the treatment of acid mine drainage.

In this study, the authors report a facile thermal activation of non-reactive cryptocrystalline magnesite and explore its application on the treatment of acid mine drainage (AMD). The primary aim was to optimize the calcination-water interface reactive conditions. Parameters evaluated include calcination temperature, calcination time, AMD-calcination temperature interface, and AMD-calcination duration interface. PHREEQC geochemical modelling was also applied to substantiate obtained results. The results indicated that the formation of MgO and CaO increase with an increase in calcination temperature and time. The optimum temperature and calcination time were observed to be 800 °C and 30 min in the furnace. The pH was observed to increase with an increase in calcination temperature and time but reached equilibrium at 800 °C and 30 min respectively. Geochemical modelling validated the formation of gypsum with attenuation in Ca ions and predicted the formation of MgSO. Metal species were observed to precipitate with an increase in pH. At 700 °C, Fe was completely removed, while Al, and Mn were completely removed from an aqueous system at 800 °C. This novel study invented the new calcination condition for non-reactive cryptocrystalline magnesite and proved its potential application in wastewater treatment. The calcination conditions were very short and therefore will save industries energy due to replacement of uneconomical and less environmental friendly pre-treatment options that lead to environmental degradation.